diff --git a/source/core/rendering/scene/hw_flats.cpp b/source/core/rendering/scene/hw_flats.cpp
index 2be5262c7..f7d61fd0e 100644
--- a/source/core/rendering/scene/hw_flats.cpp
+++ b/source/core/rendering/scene/hw_flats.cpp
@@ -366,7 +366,7 @@ void HWFlat::ProcessFlatSprite(HWDrawInfo* di, spritetype* sprite, sectortype* s
 	z = sprite->z * (1 / -256.f);
 	if (z == di->Viewpoint.Pos.Z) return; // looking right at the edge.
 
-	visibility = sectorVisibility(&sector[sprite->sectnum]);// *(4.f / 5.f); // The factor comes directly from Polymost. No idea why this uses a different visibility setting. Bad projection math?
+	visibility = sectorVisibility(&sector[sprite->sectnum]) *(4.f / 5.f); // The factor comes directly from Polymost. What is it with Build and these magic factors?
 
 	// Weird Build logic that really makes no sense.
 	if ((sprite->cstat & CSTAT_SPRITE_ONE_SIDED) != 0 && (di->Viewpoint.Pos.Z < z) == ((sprite->cstat & CSTAT_SPRITE_YFLIP) == 0))